The present invention is directed to the field of animal nutrition. Specifically, the present invention relates to the use of high oleic feed sources to lower the cholesterol levels and/or alter the fatty acid content in eggs.
As public awareness of the dangers of cholesterol has increased in recent years, a number of popular food products have drawn criticism for containing high levels of cholesterol. Eggs are among the maligned products that have suffered because of a public perception that eggs are unhealthy.
As a result of concern over cholesterol intake, a market has developed for egg products having reduced cholesterol. Many of these reduced cholesterol products are produced using additional processing steps after collection of the eggs, which add substantial cost to the production process. For example, U.S. Pat. No. 5,780,095 to Jackeschky, PCT application WO 99/56565 to Lederer, PCT application WO 94/05166 to Hsieh and European patent EP 0607120 to Oakenfull each describe these types of processes.
Also, as the consumer""s knowledge of cholesterol has increased, most consumers have become aware of the difference between low density lipoproteins (LDL), often referred to as bad cholesterol, and high density lipoproteins (HDL), often referred to as good cholesterol. Thus, it would be beneficial to produce an egg with increased levels of HDL and decreased levels of LDL.
Attempts have also been made to reduce egg cholesterol by modifying the feed given to the egg-producing animals. For example, fibrous feed ingredients, such as barley, and feed additives, such as copper, iodine, wood shavings, human cholesterol reducing agents and other specialty chemicals have been utilized in an effort to reduce egg cholesterol. U.S. Pat. Nos. 5,665,375 to Meier, 5,246,717 to Garwin, 4,764,531 to Nissen and European Patent EP 0978236 each describe this type of approach. These types of feed and feed additives have proven disadvantageous for a number of reasons: they are typically expensive, increase feed costs, are not available in continuous supply, occupy valuable space during the feed mixing process, result in environmental contamination and/or have undesirable effects on the animal.
In addition to cholesterol, fatty acid composition of the diet is believed to have an impact on human health. Mono-unsaturated fatty acids, such as oleic acid, are believed to be nutritionally more favorable for the human diet. In addition, mono unsaturated fatty acids, such as oleic acid, are more stable against oxidation than some other fatty acids and thereby reduce the tendency of food products with a greater proportion of oleic fatty acids to become rancid or contain off flavors. Attempts have been made to feed poultry supplements high in oleic acid, such as olive oil, as described in Watkins, B. A. and Elkin, R. G., 1992, Dietary Modulation of Oleic and Stearic Acid in Egg Yolks, Journal of Food Composition and Analysis 3(3):209-215. However, this method has the disadvantage of producing poor quality feed pellets if the supplement is present above a certain level. Feed supplements such as high oleic sunflower seeds have been tried, but these have the disadvantage of containing such a high fiber content that only a limited amount can be included in the diet.
Thus, there remains a need in the art for a method of lowering the cholesterol levels and/or altering the fatty acid composition of animals and eggs without requiring substantial additional process steps, feed additives or non-optimum feed ingredients.
The present invention provides a method of reducing cholesterol and/or altering the fatty acid content in eggs. The method includes feeding the animals a high oleic feed source, and may be practiced individually or in combination with known methods of layer feeding and egg processing, including those involving a further reduction in cholesterol or alteration of fatty acids. As used herein, xe2x80x9cfeed sourcexe2x80x9d refers to sources that provide a substantial portion of the nutritional and caloric requirements of the animal, rather than sources, such as mineral supplements, that provide limited nutritional and caloric value. For example, feed sources useful in the present invention include soybeans or cereal grains such as corn, sorghum, barley, rye, wheat, rice, millet, processed products derived from the above or mixtures thereof. As used herein, the term xe2x80x9ctotal feed sourcexe2x80x9d refers to the total amount of grain and soybeans used as a feed source and includes both high oleic grain and soybeans (the high oleic feed source) and any non-high oleic grain and soybeans used in the feed source.
Specifically, the method of reducing cholesterol and/or altering the fatty acid profile of the egg comprises providing a feed source comprising a high oleic feed source with at least 3.5% percent weight oleic acid when measured on a dry weight basis. The high oleic feed source is preferably high oleic corn, or more preferably high oleic high oil corn. After the feed source has been fed, the egg is collected. Any species of poultry may be used in this invention, although layer hens are preferred. Some non-exhaustive examples of poultry include laying hen or layer, turkey, emu, ostrich, duck, and goose.
The egg yolks produced by the above method have at least 5.0% less total cholesterol as compared to a normal egg yolk, preferably at least 7.8% less total cholesterol. Similarly, eggs produced by the above process have at least 3.1% less low density lipoprotein as compared to a normal egg, and preferably at least about 5.9% less low density lipoprotein. Further, eggs produced by the above process have at least 3.2% more high density lipoprotein as compared to a normal egg, and preferably at least about 8.7% more high density lipoprotein. A xe2x80x9cnormal eggxe2x80x9d is defined as an egg produced by an animal fed conventional feed sources containing conventional amounts and forms of oil with conventional amounts of oleic acid.
The present invention is directed to a method of reducing cholesterol in eggs and/or to a method of altering the fatty acid profile of eggs. The present invention is also directed to eggs and egg products containing reduced cholesterol and/or altered fatty acid profiles.
Regular corn typically contains about 2.5 to about 5.1 weight percent oil, based upon the total dry weight of regular corn. The oil content of high oil corn is typically at least greater than 5.1 weight percent and more preferably at least about 6.0 weight percent. Some high oil corn varieties have been developed with an oil content of about 12.0 weight percent, or more, based on the total dry matter weight of the high oil corn.
The oleic acid concentration in the oil of regular corn typically ranges from about 20 weight percent, to about 30 weight percent, based upon the total weight of the oil in the regular corn. The oleic acid concentration in the oil of high oleic corn is typically at least about 45 weight percent, more preferably at least about 60 weight percent, and even more preferably at least about 64 weight percent, based upon the total weight of the oil in the high oleic corn. Some high oleic varieties have been developed with an oleic content of about 75 weight percent, or more, based on the total weight of the oil in the high oleic corn, and these would be most preferable for use in the present invention.
Any variety of high oleic corn with sufficient oleic levels may be used in the present invention. An example of a high oleic corn variety is described in PCT application WO 92/01367 to Alexander. However, most preferable is the use of a variety that has the high oleic trait in combination with a high oil trait, as this variety will have the highest oleic levels when measured on an absolute basis. A variety with the high oleic trait in combination with a high oleic trait is described in PCT application WO95/22598 to Leto. High oleic high oil corn is available from DuPont Specialty Grains in Johnston Iowa. The corn used in the present invention is preferably ground and mixed into feed. The corn may be fed in mash, crumble or pellet form, and used with or without additional feed ingredients.
The oil of the high oleic high oil corn typically has the fatty acid composition set forth in Table 1. The oleic acid concentration in the oil of high oleic high oil corn is typically at least about 50 weight percent, more preferably at least about 60 weight percent, and most preferably at least about 64 weight percent, based upon the total weight of the oil in the high oleic high oil corn.
 
A soybean variety with higher oleic acid levels than commodity soybeans has also been developed and is available from DuPont Specialty Grains of Johnston, Iowa. This soybean typically contains about 83% oleic acid and 3% linoleic acid. This high oleic soybean is suitable for use in the present invention, either alone or in combination with high oleic corn.
Surprisingly, it has been discovered that the high oleic feed source, when fed to poultry, reduces cholesterol levels eggs produced by the poultry. It has also been discovered that the high oleic feed source, when fed to poultry, causes an increase of oleic acid, including a surprising increase in the cis-isomer form of oleic acid. As the cis double bond isomer is more flexible that the trans double bond isomer, this is an advantage of the present invention, since cis-isomer fatty acids are believed to have health advantages over trans-isomer fatty acids.
High oleic oilseed(s) and high oleic high oil grain(s) may be fed to poultry either separately or in any combination with each other. Additionally, high oleic soybeans and high oleic high oil corn may be combined with other components to form a feed composition that is fed to poultry. Some non-exhaustive examples of such feed components include water; beans, such as regular soybeans; grains, such as regular corn; plant-based oils; plant-based meals, such as soybean meal and/or corn meal; animal-based protein meals, such as meat-based meal and bone meal; fatty acids; commercially available formula feeds; vitamin and/or mineral supplements; and any mixture of any of these.
After the high oleic high oil grain is fed to the poultry, eggs produced by the bird may be collected and processed for later sales as egg products, such as whole eggs, pasteurized eggs, liquid whole egg, liquid yolk or any other further processed product.